Which of the following is a correct set of homologous organs?

Consider the following comments about saponification reactions:

(I) Heat is evolved in these reaction.

(II) For quick precipitation of soap sodium chloride is added to the reaction mixture.

(III) Saponification reactions are special kind of neutralization reactions.

(IV) Soaps are basic salts of long chain fatty acids.

The correct comments are:

A student has to perform the experiment "To identify the different parts of an embryo of a dicot seed." Select from the following an appropriate group of seeds:

A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building about 1km far from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen the student should slightly move the

To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always: